Synergistic Crystallization Modulation and Defects passivation via Additive Engineering Stabilize Perovskite Films for Efficient Solar Cells

• Published in: Advanced functional materials 2023-06, Vol.33 (24), p.n/a
• Main Authors: Yuan, Xiangbao, Li, Ru, Xiong, Zhuang, Li, Peiyuan, Odunmbaku, George Omololu, Sun, Kuan, Deng, Yehao, Chen, Shijian
• Format: Article
• Language: English
• Subjects: additives; Bonding strength; Circuits; Crystal defects; Crystal growth; crystal orientations; Crystal structure; Crystallization; defects passivation; Grain boundaries; Grain size; Humidity; Hydrogen bonding; Ionic interactions; Lead compounds; long‐term stability; Materials science; Metal halides; perovskite solar cells; Perovskites; Photovoltaic cells; Solar cells; Strong interactions (field theory); Structural stability; Thermal stability
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202215096

Organic‐inorganic lead halide perovskite are promising photovoltaic materials, but their intrinsic defects and crystalline quality severely deteriorate the solar cells efficiency and stability. Herein, potassium 1,1,2,2,3,3‐hexafluoroprop‐ane‐1,3‐disulfonimide (KHFDF) is introduced into PbI2 precursor solution to passivate various defects and improve the crystalline quality of perovskite films. It is found that KHFDF can inhibit PbI2 crystallization, thus tuning the crystal orientation and growth of perovskite films. Furthermore, KHFDF with dual‐functional sulfonyl group cannot only passivate grain boundaries (GBs), but also passivate the defects at GBs via strong interaction with undercoordinated Pb2+ and/or hydrogen bonding with FA+, while the K+ counter cations allow ionic interaction with undercoordinated I−. As a result, the KHFDF‐modified films exhibit high quality with a larger grain size and a reduced trap‐state density, thereby suppressing the trap‐state nonradiative recombination. And the devices show a champion efficiency up to 24.15%, benefiting from a sharp enhancement of open‐circuit voltage (Voc) of 1.183 V and fill factor of 81.78%. In addition, due to the enhanced humidity tolerance and chemical structure stability, the devices exhibit excellent long‐term humidity and thermal stability without encapsulation. Potassium 1,1,2,2,3,3‐hexafluoroprop‐ane‐1,3‐disulfonimide (KHFDF) is introduced into PbI2 precursor solution to passivate various defects and improve the crystalline quality of perovskite films. Assisted by Lewis coordination, hydrogen bonding, and ionic interaction between KHFDF and perovskite, better crystal orientation and reduced trap‐state density perovskite crystallites are achieved, yielding a power conversion efficiency of 24.15% and long‐term humidity stability and thermostability.